Search in
Sort by:

Question Status:

Search help

  • Simple searches use one or more words. Separate the words with spaces (cat dog) to search cat,dog or both. Separate the words with plus signs (cat +dog) to search for items that may contain cat but must contain dog.
  • You can further refine your search on the search results page, where you can search by keywords, author, topic. These can be combined with each other. Examples
    • cat dog --matches anything with cat,dog or both
    • cat +dog --searches for cat +dog where dog is a mandatory term
    • cat -dog -- searches for cat excluding any result containing dog
    • [cats] —will restrict your search to results with topic named "cats"
    • [cats] [dogs] —will restrict your search to results with both topics, "cats", and "dogs"

Office Holiday

Epic Games' offices will be on holiday from June 22nd to July 7th. During this period support will be limited. Our offices will reopen on Monday, July 8th. 

Overlaps Event on child component of Leap Motion Hand


I'm trying to accomplish a 3D menu attached to the Left hand of my character . I decided to re-post my issue there because I got the same issue on a BasicFPSProject. It may be a bug, so i'm going to explain the basic implementation to get this issue. I'm using Leap motion, mounted on a Oculus DK2. I'm not able to reproduce this issue in normal mode (no HMD), so the issue demonstration is from an HMD view.

The maIn issue is that one hand overlaps a Box collision where it shouldn't. I've created a BoxCollisionActor, which is basically an actor with a cube (debug purpose) and a box collision of the same size. box Collision actor

I've attached this custom box to my left Hand, and update its relative transform in order to keep the box around the hand.

Box collision child component

Cube transform update

Last step is to assign action ot the overlaps event of the box. So i check if it is the right hand and then print a message. overlap event actions

This issue can be seen during an hand movement, so i made a short video showing the good and bad calls of the Overlaps event. ==> https://youtu.be/JCzRByB7P2c

Sorry for the video deformation, it's the ouput of 'hmd mirrror mode 4'

Is this s Bug ? Did I miss something to update the box collision transform ? It's like the boxCollision is well placed but there is another invisible copy somewhere calling the Overlaps event.

Thansk for your time.

[1]: https://answers.unrealengine.com/questions/457940/false-positives-overlaps-on-box-collision.html

Product Version: UE 4.12
more ▼

asked Jul 25 '16 at 02:42 PM in Bug Reports

avatar image

30 7 12 13

avatar image Matt.Williams Jul 25 '16 at 07:07 PM

Hey Marcassin,

Can you run the "Show Collision" console command and see if there are any rogue collision volumes that might be a part of your cube mesh actor?

I've been testing this outside of VR today and haven't been able to repro the issue.

-Matt W.

avatar image Marcassin__ Jul 25 '16 at 11:59 PM

Hi Matt, Thanks for your time for testing.

I've tried the 'Show Collision' command, but i can't see any bad collision box. During debugging time I've noted that the time between events BeginOverlap and EndOverlap is very short for the "false" collisions. Set 'NoCollision' as Collision preset for the cube component didn't change the issue.

I've made another video to show the good box collision visible, with the good and false overlaps. I can't see any wrong box (around the cube or the right hand). You can see the time difference between begin and end of the good/false overlaps with the visibility of the cube. I had to let the ingame debug visible to show the false overlaps.

As i try to show, the "false" box collision is in one point, and quite hard to find, as it seems to move a little every simulation.


The "indesired boxcollision" moves with the left hand, but do not has exaclty the same 3D transformation as the hand. From the hands actor I moved the box to put it on the other side of the left hand. The bad box moves too (took me some second before finding it).


I've made another short test, i'm unable to reproduce this issue without headset. (im gonna test again in case it's very hard to find) I'm gonna start from an empty projet to check if there is a bad component somewhere.

avatar image Matt.Williams Jul 26 '16 at 02:37 PM

Somehow I suspect it has something to do with the Box Blueprint itself. Can you try making the cube just a Static Mesh Component and setting up the same logic?

avatar image Marcassin__ Jul 26 '16 at 03:48 PM

Hi, I've made a very basic setup in a empty project. One GameMode to spawn my Character. One Hands blueprint which inherits from LeapRiggedEchoHands. Here is the only Blueprint i've filled

alt text

One Character Blueprints with a SceneComponent, a camera attached, then the hands BP attached.

alt text

I got the same issue, and (forgot to activate in video) 'show collision' doesn't show any wrong collision.


I'm gonna be able to test in few days with CV1 and another LeapMotion (If you can't reproduce this issue, i'm afraid there is a hardware issue in my Leap controller).

Tell me if you need more information, more test ...

Thanks for your time Matt :)

EDIT : hmm misspelled the "hmd mirror mode", tell me if you want a new video.

avatar image Matt.Williams Jul 26 '16 at 03:57 PM

Oh wait, you're setting the transform on tick?! That wasn't in the original screenshot.

It's attached to the parent (left hand), so you don't need to set the transform on tick. It will stay attached to a skeletal mesh as long as you give it a parent socket (lf_wrist). Try disconnecting the tick event and maneuvering the Cube Component in the blueprint viewport to the right position (or doing it once on BeginPlay).

-Matt W.

EDIT: Basically what I think is happening is the attachment and the tick event are both trying to set the location of the box component, therefore the engine thinks the box is in two locations at the same time.

avatar image Marcassin__ Jul 27 '16 at 01:56 PM

Hi Matt,

I wasn't aware of the existence of mesh sockets, I realized I had to do the transform myself seeing that seting only as child component doesn't modify the location.

Anyway, I've got the same issue using parent socket. I've set up a new projet using mesh socket for the cube transform. There is no more transform onTick (Sorry for that incomplete screenshot at first) Skeletal Mesh Socket

And spawn a CubeActor linked to this socket

alt text

The cube is well placed and follow the wrist as desired, but i've got the same issue.

Project set up : https://youtu.be/FrioXs2JA0s

Collision bug : https://youtu.be/Q2f5h7TQciI

I've packaged the first basic projet, and send to a frien to test, he wasn't able to reproduce the issue, with exactly the same project (with the transform on tick). I'm gonna send to him this new project using socket. If he doesn't have the wrong collision, I'm gonna think about change my Leap. And maybe suspend this thread as long i'm the only one to get this one, and it may not be a ue4 bug.

wristsocket.png (297.0 kB)
attachtosocket.png (102.8 kB)
(comments are locked)
10|2000 characters needed characters left
Viewable by all users

1 answer: sort voted first

As others people cannot reproduce this issue, I'm thought the problem was from the devices, and not from the engine. I'm gonna make some test again with another Leap but I mark this post as resolved as long i'm not able to reproduce the issue with others devices.

Thanks to Matt.Williams for the following

more ▼

answered Jul 28 '16 at 03:07 PM

avatar image

30 7 12 13

avatar image Matt.Williams Jul 29 '16 at 07:29 PM

Thanks for going the extra mile and testing with different hardware. Let me know how it works out and if it continues to occur.

(comments are locked)
10|2000 characters needed characters left
Viewable by all users
Your answer
toggle preview:

Up to 5 attachments (including images) can be used with a maximum of 5.2 MB each and 5.2 MB total.

Follow this question

Once you sign in you will be able to subscribe for any updates here

Answers to this question